The Drell River flows through the Eastern Lands. It marks the eastern border of Tortall. Its neighbours in the Drell's eastern bank are Tyra in the southern parts and Tusaine. Farther north the Drell also functions as natural border between Scanra and Galla. On its southern end the Drell River opens out into the Great Inland Sea.
The land rights of the River Drell were the cause of much dispute between Tortall and its neighbouring country to the East, Tusaine. Normally one to avoid conflict, King Roald I of Conté sends troops to defend the Tortallan border. As Prince Jonathan of Conté's squire, this is the first time that Alanna of Trebond experiences battle.
During the war, Alanna is magical kidnapped while on sentry duty (while others fall alseep under the influence of a mysterious, fog) and is held prisoner by Tusaine forces. Notable amongst the captors is King Ain's brother, Jemis who had been spying on the Tortallans under the name Jem Tanner.
The Tortallans are ordered not to attempt a rescue, but headed by Jonathan, a small group sneaks into Tusaine's camp and free Alanna and her fellow hostages. The logic is that King Roald can not execute his own son for treason.
The Drell conflict is an important event in Alanna's life for several reasons. Not only does she confront Duke Roger of Conté and his evil intentions but she also comes to terms with and develops the use of her healing Gift. Also, the war marks the beginning of Alanna's physical relationship with Jonathan.